JP2007011356A - Electrophotographic photoreceptor and electrophotographic imaging apparatus equipped with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor for a blue-violet light source capable of realizing high resolution using a blue-violet light source as an exposure light source, and an electrophotographic imaging apparatus equipped with the electrophotographic photoreceptor. <P>SOLUTION: In the electrophotographic photoreceptor, a latent image is formed on a photosensitive layer using a blue-violet exposure light source having a wavelength of 380 to 450 nm. The outermost surface of the photosensitive layer includes a charge generating material, a charge transporting material and a binder resin. The light transmittance of the photosensitive layer is 1.0×10<SP>-1</SP>to 1.0×10<SP>-3</SP>% in the light exposure wavelength. The electrophotographic imaging apparatus equipped with the electrophotographic photoreceptor is also provided. High quality images with high resolution can be obtained using the blue-violet exposure light source having a wavelength of 380 to 450 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member and an electrophotographic image forming apparatus employing the same, and more specifically, an electrophotographic photosensitive member that realizes high resolution by using a blue-violet light source as an exposure source and the same. The present invention relates to an electrophotographic image forming apparatus.

  A semiconductor laser that is widely used as an exposure light source for an electrophotographic image forming apparatus has an oscillation wavelength in the near infrared region near 800 nm of AlGaAs / GaAs system from the beginning. The reason why such a long wavelength semiconductor laser was selected, which is not in the visible light wavelength region where most conventional electrophotographic photosensitive members are sensitive, is to obtain a semiconductor laser that stably oscillates in the short wavelength region. It was because there was not. For this reason, electrophotographic photosensitive members for laser printers have developed a unique development different from that for copying machines. That is, instead of the conventional inorganic field electrophotographic photosensitive member, a multilayer electrophotographic photosensitive member using an organic compound having sensitivity in a long wavelength region as a charge generation layer has come to play a central role. As described above, in the electrophotographic image forming apparatus, the light source for exposure and the electrophotographic photosensitive member have always been developed with a close relationship.

  In recent years, in order to improve the image quality of an output image of an electrophotographic image forming apparatus, higher resolution is being accelerated. As part of the response on the device for such purposes, access in the optical plane is relatively easy. That is, if the spot diameter of the exposure beam is reduced to increase the writing density, the resolution is improved. However, it has been clarified that a semiconductor laser having an oscillation wavelength in the near infrared region, which is often used as an exposure source, cannot obtain a clear spot contour even if the beam diameter is reduced by operating the optical system. This is a phenomenon that cannot be avoided due to the diffraction limit of laser light. In order to improve this, it is effective to shorten the wavelength of the light source. This is because the lower limit of the spot diameter D is a function that is directly proportional to the wavelength λ of the laser light and is expressed by the following equation.

D = 1.22λ / NA
Here, NA represents the lens numerical aperture.

  On the other hand, the development of light emitting diodes (LEDs) and semiconductor lasers with a short oscillation wavelength has progressed smoothly, and a red semiconductor laser having an oscillation wavelength around 650 nm has already been put into practical use since the beginning of the 1990s. In 1991, a ZnSe laser emitting at 450 nm was announced, but due to the short life, it could not be put to practical use. However, a practical GaN-based blue LED was developed in 1993, and a long-lived GaN-based blue-violet semiconductor laser that emits light at about 410 nm was developed in 1995. These are currently in practical use as important light sources for blue display devices and high density optical disks.

  Patent Document 1 discloses a technique of using an electrophotographic photosensitive member containing a charge generating material on the surface of a photosensitive layer in an electrophotographic image forming apparatus using such a blue semiconductor laser having a wavelength of 400 to 500 nm. Yes. This technology solves the problem that in a general photoreceptor having a charge transport layer as a surface layer, blue laser light is absorbed by the charge transport layer and sufficient sensitivity cannot be obtained. This is to prevent a reduction in resolution due to charge diffusion that occurs during movement within the device.

  However, as a photoreceptor having a charge generation material on the surface layer, a single layer type photoreceptor containing an organic pigment which is a charge generation material dispersed in an electrically insulating binder resin, and a charge dispersed in the binder resin are used. There is a multilayer photoreceptor in which a thin charge generation layer containing a generating substance is formed on a charge transport layer. In such a photoconductor, the concentration of the charge generating material must be kept high in order to obtain good electrophotographic characteristics. However, if the concentration of the charge generating material is kept high as described above, there is a problem that rapid deterioration occurs due to the influence of corona discharge or the mechanical durability is low. In order to solve such problems, a single-layer type photoreceptor containing a charge generation material and a charge transport material dispersed in a binder resin, and a charge generation material and a charge transport material dispersed in the binder resin There is a multi-layer type photoreceptor in which a thick charge generation layer containing is formed on a charge transport layer. In such a photoreceptor, since the surface layer contains the charge transport material together with the charge generation material, the charge generation material can be at a relatively low concentration. Therefore, the photoconductor of such a form is not easily affected by corona discharge, and can increase the content of the binder resin, so that it has high mechanical durability and is more practical.

Japanese Patent Laid-Open No. 9-240051 JP-A-8-106165

  However, as disclosed in Patent Document 1, when a photoconductor having a photosensitive layer containing a charge transport material together with a charge generating material is applied to an electrophotographic image forming apparatus using a blue-violet light source, It became clear that it was difficult to obtain high resolution as expected. This is because, in the case of a photoconductor having such a configuration, the concentration of charge generation material in the surface layer is low, so that the irradiated light penetrates into the photosensitive layer to some extent and is scattered and diffused. It is believed that there is. Furthermore, in such a blue-violet light region, since both light absorption by the charge generation material and light absorption by the charge transport material are mixed, the amount of light absorption can be simply increased only by the concentration of the charge generation material. There is a problem that it cannot be controlled. In fact, according to the example of Patent Document 1, the photoconductor of Production Example 3 including the charge transport material in the surface layer exhibits lower sensitivity in the blue light region than the other two photoconductors not including the charge transport material. This is considered to be the reason for this. Also, this technique does not teach or suggest any relationship between the resolution of the output image and the light transmittance of the photosensitive layer. Therefore, in order to obtain high resolution in an electrophotographic apparatus using a blue-violet semiconductor laser using this technique, it is necessary to solve a more important technical problem.

  On the other hand, Patent Document 2 relates to a single-layer electrophotographic photosensitive member that can obtain an image without interference fringes using an electrophotographic apparatus that uses temporary interference light as exposure light. For this reason, Patent Document 2 discloses a transmissivity at a wavelength of use of the photoconductor in a single layer type electrophotographic photoconductor including at least a charge generation material, an organic acceptor compound, and a hole transport material on a conductive substrate. Disclosed is a single layer type electrophotographic photosensitive member characterized in that the content is 10% or less. However, this uses a near-infrared wavelength with an exposure wavelength of 780 nm, and discloses a technique for increasing light absorption by a charge generating material for the purpose of preventing the occurrence of interference fringes in an image. In addition, since an acceptor compound having a large light absorption in the blue-violet light region is used, effective light energy is reduced due to light absorption by the acceptor compound, and sufficient sensitivity cannot be obtained in the blue-violet light region. .

  Accordingly, the present invention has been made in view of such problems, and an object thereof is to provide a practical electrophotographic photoreceptor capable of realizing high resolution by using a blue-violet light source as an exposure source. is there.

  Another object of the present invention is to provide an electrophotographic image forming apparatus provided with the electrophotographic photosensitive member.

In order to solve the above-described problems, according to one aspect of the present invention, there is provided an electrophotographic photosensitive member including a conductive support and a photosensitive layer formed on the conductive support, wherein the blue photosensitive layer has a wavelength of 380 to 450 nm. A latent image is formed on the photosensitive layer using a violet exposure source, and the outermost surface layer of the photosensitive layer contains a charge generating substance, a charge transporting substance, and a binder resin, and the photosensitive layer at the exposure wavelength is used. An electrophotographic photosensitive member is provided in which the light transmittance of the layer is in the range of 1.0 × 10 ^{−1 to} 1.0 × 10 ⁻³ %.

In order to solve the above-mentioned problems, according to another aspect of the present invention, an electrophotographic photoreceptor including a conductive support and a photosensitive layer formed on the conductive support, and the electrophotographic photoreceptor. A charging device for charging the photosensitive layer, an exposure device for forming an electrostatic latent image on the surface of the photosensitive layer of the electrophotographic photosensitive member by exposure using laser light, and a developing device for developing the electrostatic latent image The electrophotographic photosensitive member forms a latent image on the photosensitive layer using a blue-violet exposure source having a wavelength of 380 to 450 nm, and the electrophotographic photosensitive member forms a latent image on the photosensitive layer. The surface layer contains both a charge generation material, a charge transport material and a binder resin, and the light transmittance of the photosensitive layer at the exposure wavelength is in the range of 1.0 × 10 ^{−1 to} 1.0 × 10 ⁻³ %. An electrophotographic image forming apparatus is provided.

  In the electrophotographic photoreceptor and the electrophotographic image forming apparatus of the present invention, the photosensitive layer may be a single-layer type photosensitive layer including a charge generation material and a charge transport material dispersed or dissolved in a binder resin. .

  In the electrophotographic photoreceptor and the electrophotographic image forming apparatus of the present invention, the photosensitive layer includes a charge transport layer containing a charge transport material dispersed or dissolved in a binder resin, and a charge formed on the charge transport layer. It may be a multi-layer type photosensitive layer that is a generation layer and includes a charge generation layer containing a charge generation material dispersed or dissolved in a binder resin and a charge transport material.

  In the electrophotographic photoreceptor and the electrophotographic image forming apparatus of the present invention, the charge generation material includes a titanyl phthalocyanine compound, and the charge transport material includes a hole transport material including an arylamine compound and a naphthalene tetracarboxylic acid diimide compound. And an electron transport material containing

  Since the electrophotographic image forming apparatus of the present invention uses blue-violet light having an oscillation wavelength of 380 to 450 nm as a light source, it is advantageous for obtaining a high resolution image because the diffusion of the spot of irradiated light is greatly reduced. is there. In addition, since the electrophotographic photosensitive member of the present invention used in combination with such a blue-violet laser exposure source contains a charge generating substance on the light incident surface of the photosensitive layer, the structure of the photosensitive layer has a high resolution. It is advantageous for realization. In addition, the electrophotographic photosensitive member of the present invention has good photosensitivity characteristics while suppressing a decrease in resolution due to the photosensitive member by setting the transmissivity of the exposure source having the oscillation wavelength within a specific range. Since mechanical characteristics can be achieved, it is particularly practical as an electrophotographic photoreceptor for a blue-violet light source.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic cross-sectional view of a single layer type electrophotographic photoreceptor according to an embodiment of the present invention. Referring to FIG. 1, a single-layer photosensitive layer 2 including a charge generation material and a charge transport material dispersed in a binder resin is formed on a conductive support 1. The thickness of the single-layer type photosensitive layer 2 is usually about 5 to 50 μm, preferably 10 to 40 μm. If the thickness of the single-layer type photosensitive layer 2 is less than 5 μm, there is a problem that charging ability and sensitivity are insufficient, and if it exceeds 50 μm, there is a problem that the residual potential increases or the response speed decreases. .

  FIG. 2 is a schematic cross-sectional view of a multilayer electrophotographic photosensitive member according to another embodiment of the present invention. Referring to FIG. 2, a charge transport layer 3 including a charge transport material dispersed in a binder resin on a conductive support 1, and a charge generation material and a charge transport material dispersed in the binder resin are provided. A multi-layer type photosensitive layer 5 in which the charge generation layer 4 including the layers is sequentially laminated is formed.

  The thickness of the charge generation layer 4 is preferably 1 to 20 μm, more preferably 2 to 10 μm. If the thickness of the charge generation layer 4 is less than 1 μm, the photosensitivity and mechanical durability are insufficient, and if it exceeds 20 μm, the total thickness of the photosensitive layer 5 including the charge transport layer 3 and the charge generation layer 4 is combined. The thickness tends to be excessively thick and the electrophotographic characteristics tend to deteriorate.

  The thickness of the charge transport layer 3 is desirably 2 to 100 μm, more desirably 5 to 50 μm, and most desirably 10 to 40 μm. If the thickness of the charge transport layer 3 is less than 2 μm, the thickness is too thin and the effect of providing the charge transport layer 3 is insufficient, and if it exceeds 100 μm, the quality of the printed image tends to deteriorate. .

  In addition to the photosensitive layers 2 and 5, functional layers such as a conductive layer, an intermediate layer, and a surface protective layer may be further formed as necessary.

  The conductive support used in the electrophotographic photosensitive member of the present invention is not particularly limited as long as it is a conductive material, and includes a plate, a disk, a sheet, a belt, a drum, or the like made of metal, a conductive polymer, or the like. Can be mentioned. Examples of the metal include aluminum, vanadium, nickel, copper, zinc, palladium, indium, tin, platinum, stainless steel, and chromium. Examples of the polymer include polyester resin, polycarbonate resin, polyamide resin, polyimide resin, and mixtures thereof, and copolymers such as monomers used in the manufacture of the resin, conductive carbon, tin oxide, indium oxide, and the like. The thing which disperse | distributed the active substance can be mentioned. A metal sheet or an organic polymer sheet on which a metal is deposited or laminated may also be used.

  As the charge generation material used for the photosensitive layer, any material having sensitivity to blue-violet light used as a light source can be used. For example, azo pigments, quinone pigments, perylene pigments, indigo pigments, thioindigo pigments, bisbenzimidazole pigments, phthalocyanine pigments, quinacridone pigments, quinoline pigments, lake pigments, azo lake pigments, anthraquinone pigments Pigment, oxazine pigment, dioxazine pigment, triphenylmethane pigment, azurenium dye, squarylium dye, pyrylium dye, triallylmethane dye, xanthene dye, thiazine dye, cyanine dye, perinone compound, Various organic pigments or organic dyes such as polycycloquinone compounds, pyrrolopyrrole compounds or naphthalocyanine compounds, amorphous silicon, amorphous selenium, tellurium, selenium-tellurium alloys, cadmium sulfide, antimony sulfide, zinc oxide, sulfur Include an inorganic material such as zinc.

  In the electrophotographic photosensitive member of the present invention, the above-mentioned charge generating materials can be used alone, but two or more kinds of charge generating materials may be mixed and used.

  In the electrophotographic photoreceptor of the present invention, a hole transport material and / or an electron transport material can be used as the charge transport material.

  The hole transport material that can be used in the photosensitive layer includes, for example, pyrene-based, carbazole-based, hydrazone-based, oxazole-based, oxadiazole-based, pyrazoline-based, arylamine-based, arylmethane-based, and benzidine-based compounds. , Thiazole-based, stilbene-based, and butadiene-based compounds. Examples of the hole transport material that can be used in the photosensitive layer include polymer compounds such as poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, and pyrene-formaldehyde. Resin, ethylcarbazole-formaldehyde resin, triphenylmethane polymer, polysilane and the like.

  Examples of electron transport materials include benzoquinone, tetracyanoethylene, tetracyanoquinodimethane, fluorenone, xanthone, phenanthraquinone, phthalic anhydride, diphenoquinone, stilbenequinone, naphthalene, thiopyran. Includes electron-withdrawing low molecular weight compounds such as systems. However, the present invention is not limited to these, and an electron transporting polymer compound or pigment having n-type semiconductor characteristics may also be used. Examples of the electron transporting polymer compound having n-type semiconductor characteristics include a polymer having the structure of the above-described electron-withdrawing low-molecular compound as a main chain or a side chain. Examples of organic pigments include perylene pigments, anthanthrone pigments, perinone pigments, bisazo pigments, and inorganic pigments include titanium oxide, zinc oxide, and cadmium sulfide.

  In the electrophotographic photoreceptor of the present invention, the above-mentioned charge transport materials can be used alone, but two or more kinds of charge transport materials may be mixed and used.

  In the electrophotographic photosensitive member of the present invention, the binder resin is preferably a polymer capable of forming an electrically insulating film. Such polymers include, for example, polycarbonate, polyester, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile polymer, vinyl chloride-vinyl acetate. Polymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole, polyvinyl butyral, polyvinyl formal, polysulfone, Casein, gelatin, polyvinyl alcohol, ethyl cellulose, phenol resin, polyamide, carboxymethyl cellulose, vinylidene chloride polymer latex, polyurethane, etc. Anatta, but it is not limited thereto. Such binder resins may be used alone or in combination of two or more.

  Among the binder resins, the present inventors have used, as the binder resin, cyclohexylidene as a polycarbonate resin, among them, polycarbonate-A derived from bisphenol A or polycarbonate-C derived from methylbisphenol A. It has been found that utilizing polycarbonate-Z derived from bisphenol is desirable due to the high glass transition temperature and high wear resistance of this resin.

  In addition to such binder resins, dispersion stabilizers, plasticizers, surface modifiers, antioxidants, photodegradation inhibitors for the purpose of improving processability, environmental resistance, and stability against harmful light. Additives such as can be used.

  Examples of the plasticizer include biphenyl, biphenyl chloride, terphenyl, dibutyl phthalate, diethylene glycol phthalate, dioctyl phthalate, triphenyl phosphate, methyl naphthalene, benzophenone, chlorinated paraffin, polypropylene, polystyrene, various fluorine hydrocarbons, and the like. .

  Examples of the surface modifier include silicon oil and fluororesin.

  Although the said antioxidant is not limited to these, It contains well-known antioxidants, such as a hindered phenol type, a sulfur type, a phosphonic acid ester type compound, a phosphite type compound, an amine type compound. The light stabilizer includes known light stabilizers such as benzotriazole compounds, benzophenone compounds, hindered amine compounds, and the like.

  The photosensitive layer can be formed using a dip coating method, a ring coating method, a roll coating method, a spray coating method, or the like. In the case of a single-layer type photoreceptor, a conductive support is provided for the composition for forming a single-layer type photosensitive layer in which a binder resin, a charge generating material, a hole transport material and / or an electron transport material are dispersed or dissolved in an organic solvent. It is coated on the body and dried at about 40 to 200 ° C. for about 0.1 to about 5 hours to form a single layer type photosensitive layer. In the case of a multi-layer type photoreceptor, first, a charge transport layer forming composition in which a binder resin, a hole transport material and / or an electron transport material is dispersed or dissolved in an organic solvent on a conductive support is electrically conductive. A charge transport layer can be formed by coating on a conductive support and drying at about 40 to 200 ° C. for about 0.1 to 5 hours. Next, a charge generation layer forming composition in which a charge generation material, a hole transport material and / or an electron transport material, and a binder resin are dispersed or dissolved in an organic solvent is applied onto the charge transport layer, and about 40 to The charge generation layer can be formed by drying at 200 ° C. for about 0.1 to 5 hours.

The contents of the charge generating material, hole transporting material, electron transporting material and binder resin are not particularly limited, and the light transmittance of the photosensitive layer at the exposure wavelength is 1.0 × 10 ⁻¹ to 1. It can be selected within a range of 0 × 10 ⁻³ %.

  Since the organic solvent varies depending on the type of the binder resin, it is desirable to select and use the optimum one. Examples of such organic solvents include alcohols such as methanol, ethanol, and n-propanol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; Ethers such as tetrahydrofuran, dioxane and methyl cellosolve; esters such as methyl acetate and ethyl acetate; sulfoxides and sulfones such as dimethyl sulfoxide and sulfolane; aliphatic halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride and trichloroethane And aromatics such as benzene, toluene, xylene, monochlorobenzene and dichlorobenzene.

The light transmittance of the photosensitive layer at the exposure wavelength needs to be adjusted to be in the range of 1.0 × 10 ^{−1 to} 1.0 × 10 ⁻³ %. If the light transmittance is larger than 1.0 × 10 ⁻¹ %, the ratio of the irradiated light reaching the deep part of the photosensitive layer increases, so that the resolution of the latent image may be reduced due to energy scattering, which is not desirable. Further, when the transmissivity is smaller than 1.0 × 10 ⁻³ %, there are cases where the absorption by the charge transport material is large and the absorption by the charge generation material is large, but if the absorption by the charge transport material is large There is a problem that the photosensitivity decreases because the absorption ratio by the charge generation material decreases. On the other hand, when the absorption by the charge generating material is large, the charging property is lowered and the stability is deteriorated due to the increase in dark conductivity, which is not desirable. In order to realize such light transmittance, it is necessary to optimize the concentration of the charge generation material and simultaneously select a material having a small absorbance at a wavelength in the range of 380 to 450 nm as the charge transport material.

  The electrophotographic image forming apparatus of the present invention has normal charging, exposure, development, transfer, and fixing processes, and uses an exposure light source having an oscillation wavelength in the range of 380 to 450 nm. Examples of such light sources include GaN-based semiconductor lasers and light-emitting diodes.

  Since the electrophotographic image forming apparatus of the present invention uses blue-violet light having an oscillation wavelength of 380 to 450 nm as the light source, the diffusion of the spot of the irradiated light is theoretically half that of the conventional light source. Since it is reduced to the extent, a very high resolution image can be obtained. The electrophotographic photosensitive member used in combination with this is advantageous for realizing ultrahigh resolution even in terms of the layer arrangement structure because it contains a charge generating substance on the light incident surface of the photosensitive layer. In a conventional multilayer electrophotographic photosensitive member that has been used in an electrophotographic image forming apparatus using a laser as a light source for exposure, since the charge generation layer is on the support side, the charge generated by light irradiation is transported to the upper layer. Since the inside of the layer drifts and reaches the surface to neutralize the charged charges and form a latent image, diffusion due to charge movement inevitably occurs and a reduction in resolution cannot be avoided. In addition, the irradiation light tends to spread to the influence of refraction and scattering until it reaches the charge generation layer through the charge transport layer. On the other hand, since the electrophotographic photoreceptor of the present invention contains a charge generating material and a charge transport material on the light incident surface of the photosensitive layer, charges are generated near the surface of the photosensitive layer, and the generated charges are electrons. Since the charge of the opposite polarity charged on the surface of the photographic photoconductor is instantaneously neutralized, there is no loss due to the distance of charge transfer, and the recorded information can be reflected in the latent image as it is.

  The photoconductor of the present invention achieves good photosensitivity characteristics and mechanical characteristics while minimizing resolution degradation by the photoconductor by setting the light transmittance of the light source used within a specific range. It is further practical as an electrophotographic photoreceptor for a blue-violet light source.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, this is for illustrative purposes and the scope of the present invention is not limited thereto.

Example 1
2 parts by mass of α-type titanyl phthalocyanine and 2 parts by mass of polycarbonate Z resin (manufactured by Teijin Kasei Co., Ltd., PANLITE TS-2020) were mixed with 46 parts by mass of chlorobenzene, and then the mixture was finely dispersed by grinding with a sand mill for 1 hour. To prepare a dispersion.

  Next, 35 parts by mass of an arylamine compound of the compound (1) satisfying the following formula (1) as a hole transport material and a naphthalenetetracarboxylic acid diimide compound of the compound (2) satisfying the following formula (2) as an electron transport material 15 parts by mass and 50 parts by mass of polycarbonate Z resin were dissolved in 300 parts by mass of chloroform to prepare a solution.

The dispersion and the solution were mixed at a ratio of 1: 8 and dispersed with a homogenizer until uniform, to obtain a photosensitive layer coating solution. This coating solution was applied on an aluminum drum having a diameter of 30 mm by a ring coating method and then dried to obtain a single-layer electrophotographic photosensitive drum having a thickness of about 15 μm. The photosensitive layer of this photoreceptor was peeled off, and the light transmittance at 405 nm was measured using an ultraviolet-visible absorption spectrometer. This light transmittance was 7.5 × 10 ⁻² %.

(Example 2)
In Example 1, a photosensitive drum was manufactured by the same method as described in Example 1 except that the ratio of the dispersion to the solution was 1: 4. The light transmittance of this photoreceptor at 405 nm was 5.5 × 10 ⁻³ %.

(Example 3)
As the hole transport material, 40 parts by mass of the arylamine compound of the compound (1) and 60 parts by mass of the polycarbonate Z resin were dissolved in 300 parts by mass of chloroform to prepare a charge transport layer forming solution. This solution was applied on an aluminum drum having a diameter of 30 mm by a ring coating method and then dried to form a charge transport layer having a thickness of about 8 μm.

  Next, the dispersion and solution used in Example 1 were mixed at a ratio of 1: 2 to prepare a dispersion for forming a charge generation layer. Next, the dispersion was applied on the charge transport layer by a ring coating method and then dried to form a charge generation layer having a thickness of about 7 μm.

The transmissivity at 405 nm of the multi-layer electrophotographic photosensitive drum thus obtained was 8.9 × 10 ⁻² %.

(Comparative Example 1)
A photoconductor by the same method as described in Example 1 except that a diphenoquinone compound of the compound (3) satisfying the following formula (3) is used as the electron transport material instead of the compound of the compound (2). A drum was produced.

The light transmittance of this photoreceptor at 405 nm was 3.2 × 10 ⁻⁴ %.

(Comparative Example 2)
In Example 1, a photosensitive drum was manufactured by the same method as described in Example 1 except that the ratio of the dispersion to the solution was 1:20. The transmittance of this photoreceptor at 405 nm was 2.4 × 10 ⁻¹ %.

<Image evaluation>
The photosensitive drums produced in the examples and comparative examples were mounted on a tester obtained by modifying a commercially available laser printer, and image evaluation was performed. The specifications of the modified tester are as follows.
(+) Corona charging method, reversal development method,
Prototype LSU (Laser Scanning Unit) equipped with a 405 nm GaN semiconductor laser as the light source,
・ Laser beam spot diameter: about 20 μm
・ Print speed: 16 sheets / minute,
・ Resolution: 1200 dpi (dot per inch)

  After printing a black and white fine line and halftone dot image with one dot under the above conditions, the image was enlarged with a microscope to evaluate dot reproducibility. The density (ID) of a square solid image having a side of 10 mm was measured using a densitometer RD-900 manufactured by Gretag Macbeth.

  Table 1 summarizes the results of the above experiments.

  As can be seen from Table 1, the photoreceptors of Examples 1 to 3 according to the present invention exhibited excellent image characteristics, whereas the photoreceptors of Comparative Examples 1 and 2 could not exhibit sufficient characteristics. It was. As can be seen from the measured values of light transmittance, the photoconductor of Comparative Example 1 corresponding to the example of Japanese Patent Laid-Open No. 9-240051 having a different structure of the electron transport material when compared with Examples 1 and 2 is as follows. The transmittance at the exposure wavelength was remarkably small. In addition, since most of the light absorption is due to the electron transport material, it is insufficient to obtain a high-resolution image with high resolution at the blue-violet exposure wavelength. In Comparative Example 1, it is considered that the lack of dots is due to an increase in halftone potential, suggesting that the charge generation efficiency was reduced due to the increase in the light absorption ratio by the electron transport material. Further, in the case of the photoconductor of Comparative Example 2 in which the light transmittance is higher than the light transmittance presented in the present invention, not only the image density is low but also a decrease in resolution is observed. It can be seen that the characteristics are insufficient.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  The present invention is suitably used in the related technical field of electrophotographic photoreceptors.

1 is a schematic cross-sectional view of an electrophotographic photosensitive member having a single-layer type photosensitive layer according to an embodiment of the present invention. FIG. 5 is a schematic cross-sectional view of an electrophotographic photosensitive member having a multilayer photosensitive layer according to another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive support body 2 Photosensitive layer 3 Charge transport layer 4 Charge generation layer

Claims (8)

An electrophotographic photoreceptor comprising a conductive support and a photosensitive layer formed on the conductive support,
A latent image is formed on the photosensitive layer using a blue-violet exposure source having a wavelength of 380 to 450 nm, and the outermost surface layer of the photosensitive layer contains both a charge generating substance, a charge transporting substance, and a binder resin, An electrophotographic photoreceptor, wherein the light transmittance of the photosensitive layer at an exposure wavelength is in the range of 1.0 × 10 ^{−1 to} 1.0 × 10 ⁻³ %.   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer is a single-layer type photosensitive layer containing a charge generation material and a charge transport material dispersed or dissolved in a binder resin. The photosensitive layer is
A charge transport layer comprising a charge transport material dispersed or dissolved in a binder resin;
A charge generation layer formed on the charge transport layer, comprising a charge generation material dispersed or dissolved in a binder resin and a charge transport material; and
The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is a multilayer type photosensitive layer comprising: The charge generation material includes a titanyl phthalocyanine compound,
The electrophotographic photosensitive member according to claim 1, wherein the charge transport material includes both a hole transport material including an arylamine compound and an electron transport material including a naphthalenetetracarboxylic acid diimide compound. An electrophotographic photoreceptor comprising a conductive support and a photosensitive layer formed on the conductive support; and
A charging device for charging the photosensitive layer of the electrophotographic photoreceptor;
An exposure device that forms an electrostatic latent image on the surface of the photosensitive layer of the electrophotographic photosensitive member by exposure using laser light; and
A developing device for developing the electrostatic latent image;
An electrophotographic image forming apparatus comprising:
The electrophotographic photoreceptor is
A latent image is formed on the photosensitive layer using a blue-violet exposure source having a wavelength of 380 to 450 nm, and the outermost surface layer of the photosensitive layer contains both a charge generation material, a charge transport material and a binder resin, An electrophotographic image forming apparatus, wherein the light transmittance of the photosensitive layer at an exposure wavelength is in the range of 1.0 × 10 ^{−1 to} 1.0 × 10 ⁻³ %.   6. The electrophotographic image forming apparatus according to claim 5, wherein the photosensitive layer is a single layer type photosensitive layer containing a charge generation material and a charge transport material dispersed or dissolved in a binder resin. The photosensitive layer is
A charge transport layer comprising a charge transport material dispersed or dissolved in a binder resin;
A charge generation layer formed on the charge transport layer, comprising a charge generation material dispersed or dissolved in a binder resin and a charge transport material; and
The electrophotographic image forming apparatus according to claim 5, wherein the electrophotographic image forming apparatus comprises a multilayer type photosensitive layer comprising: The charge generation material includes a titanyl phthalocyanine compound,
The electrophotographic image forming apparatus according to claim 5, wherein the charge transport material includes both a hole transport material including an arylamine compound and an electron transport material including a naphthalenetetracarboxylic acid diimide compound.

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